Puxing PX888 UHF
Compliance Test

Compliance testing to ascertain if this radio meets ITU guidelines for spurious emissions.

Puxing PX888 UHF Final Grade: PASS

The Puxing PX888 UHF amateur radio sample tested in our evaluation exhibited outstanding performance on its dedicated 70 cm band. Our measurements detected no spurious emissions exceeding the permissible limits set by ITU guidelines.

It is important to note that this was a single-sample test and it is possible other samples could vary in performance.

Tests performed in Surrey, BC, Canada on November 16, 2024 by Reg Natarajan.

Power Output Testing

Power output was measured using a Surecom SW-33 Plus into a dummy load. The radio was set to maximum power. The ITU guidelines for spurious emissions require measurements of "the power (W) supplied to the antenna transmission line".  That requirement makes this separate power measurement necessary, as it is incorrect to measure relative to the fundamental (f0).  All numbers have been rounded.

70cM

446.000 Mhz

5.3 watts

Using the ITU formula of 43+10log(P) dB, spurious emissions for a signal of 5.3 watts must be at least 50.2 dB below the power supplied to the antenna transmission line.  5.3 watts is approximately 37.2 dBm, which means no spurious signal may exceed -13 dBm, or approximately 50 microwatts.

Spurious Emissions Testing

Spurious emissions were measured using a Tiny SA Ultra.  The radio was set to maximum power and was connected to the TinySA through an attenuator. It is important to understand that the graphs below are using a decibel scale, not a linear scale.  If a spurious emission spike appears to be almost as tall as the fundamental, that does not mean it is emitting almost as much power.  Refer to the raw data shown. 

UHF 70 cm Band Test Results: PASS

Raw Data 70cm

All numbers have been rounded

Power at Antenna: 37.2 dBm (5.3 watts)

Fundamental (f0): 35.6 dBm (3.6 watts)


The Puxing PX888 UHF sample that we tested displayed one significant harmonic emission above the 70 cm band fundamental in our testing, but that emission was below the -13 dBm level permitted by the ITU, which means this radio remains compliant with ITU guidelines on spurious emissions


Comments

Many thanks to Ron VA7CPL from the Langley Amateur Radio Association for the use of his radio for testing.

~Reg Natarajan VA7ZEB / HJ1ZEB, November 16, 2024